Process for purifying aluminum and its alloys.



uninn STATES PAT GRnNviLLn MELLEN, or EAST ORANGE, NEW JERSEY,ASSIGNOIR, or ONE-HALF r0 7 PROCESS FOR PURIFYING ALUMINUM ANDITSALLOYS.

Specification of Letters Patent.

No Drawing. Original application filed'June 26, 1912, Serial No.706,041.

filed. October 10, 1912. Serial No. 725,059.

' UNITED ALUMINUM INGO'I COMPANY, A CORPORATION OF NEW ,YORK.

Divided and this application purifying molten aluminum or its alloysfrom impurities, such as aluminum oxid,

and is a division of my application Serial Number 706,041, filed June26, 1912. The impurities are largely aluminum oxid, resulting from thesuperficial oxidation of the metalwhen molten; said oxids being stirredin the mass of the metal and mechanically held therein.

If a material which is non-oxidizing, and which boils at a temperaturelower than the melting-point of aluminum, and of lower specific gravitythan aluminum, be injected into the ower level of the molten metal, thevapors on arising through the metal will have the result of carrying theimpurities to the surface where they may dissolve or combine with a fluxon the surface; or if such impurities chemically or mechanically combinewith the vaporizable material added, the resulting compound or mixturewill rise to the surface, from which it may be removed in any suitable'manner. I have found that the addition of sulfur to molten aluminum orits alloys has this property; and on injecting solid sulfur to thebottom of a container filled with the molten metal or alloy,'t-he sulfurboils and its vapors passing through the molten metal stir itvigorously,v combining with the impurities either mechanically orchemically and carry them to the surface, from which they may beremoved. It is advantageous to also add a fusible material having a lowspecific gravity which acts as a flux and serves to mechanically entrainor to chemically combine with the impurities, carrying them to thesurface, from which they may be removed. I have further found that byadding sodium chlorid (salt) to molten sulfur, thoroughly stirring,

and casting into rods, I obtain a material particularly adapted toremove the impurities above referred to. A rod of this material isplunged into the molten metal or alloy, and stirred, the salt meltingand the sulfur boiling from the surface of the rod, the sulfur vaporsbubbling through the molten metal, while the molten salt passes up moreslowly. The combined action of the sulfur "apors and salt is to free themetal from its impurities by carrying them to the surface, where theyform. a flux or scoria with the salt, or with any other flux present,and from which they can readily be removed. The treatment ofthe moltenmetal or alloy is of greater or less duration depending upon thequantity of impurities present. The rod of salt and sulfur may containfrom 0 to 70 per cent. of salt, an excess of salt or away; its vaporscausing. violent ebullition of the mass of metal, thoroughly agitatingit,

and carrying its impurities to the surface.

Instead of sodium chlorid, I may melt together sulfur and sodium sulfid.I

.To the surface of the molten metal maybe added a flux such as sodiummeta-phosphate or zinc chlorid which fuses readily and combines with thesalt and sulfur scoria or Patented Apr. 14, ram.

dross; it will further serve to effect a ready separation ofthe scoriafrom the molten metal.

I have found that aluminumscrap from different sources, such as scrapsheet, turnings, and castings that have been corroded by use andexposureto air and water, and which, if melted without any purifyingagent, would produce a very impure metal,

will, upon being treated with the purifying agency herein described,produce a metal equal in every way to new and hitherto un- I used metal.

I claim: 1. The process of purifying aluminum 3. The process ofpurifying aluminum and its alloys, comprising adding to the and itsalloys, comprising subjecting the I melted metal to a sulfur-containingpurifymelted metal to the action of sulfur vapors l ing agent, andreacting upon theimpurities bubbling therethrough. in the melted metalwith the sulfur in the 4:. The process of purifying aluminumsulfur-containing agent.

5 and its alloys, comprising adding sulfur and In testimony whereof Iafiix my signature 15 a fusible solid to the molten metal, said solid inpresence of two witnesses. having a lower specific gravity than theGRENVILLEMELLEN. metal. Witnesses:

5. The processof purifying aluminum JOHN O.B1cELow, 10 and its alloys,comprising subjecting the STUART A. YOUNG.

